This invention relates to parallel peripheral interfaces associated with digital computers. More particularly, the invention concerns a compact high-speed bi-directional hardware interface between a master controller, e.g. a computer, and one or more client controllers, e.g. peripherals.
The invention provides apparatus for the transfer of data/command between a master controller and one or more client controllers. The apparatus in accordance with the invention includes a bi-directional data bus for conveying plural bits of data or command between a master controller and one or more client controllers; direction signal controlling the direction in which data or command bits are conveyed on the data bus as between the master controller and a connected one of the one or more client controllers; a pair of ready signals including a transmit ready signal asserted by a source of data or command bits placed on the data bus and including a receive ready signal asserted by a destination for the data or command bits placed on the data bus; and a clock signal for indicating the presence of valid data or command bits on the data bus on a leading or trailing edge thereof. Preferably, a command/data signal is also provided to indicate the type of information placed on the data bus by the source.
In accordance with one aspect of the invention, the pair of ready signals includes a bidirectional transmit ready signal and a bi-directional receive ready signal corresponding to each one of the one or more client controllers, and wherein the functions of the transmit ready signals and the receive ready signals within the interface are modified by the state of the direction signal, whereby under a first state of the direction signal a transmit ready signal is asserted by the master controller to select one of the one or more client controllers as a destination for the data or command bits placed on the data bus and a corresponding receive ready signal is asserted by the one client controller to indicate that the one client controller is ready to receive the data or command bits placed on the data bus and whereby under a second state of the direction signal a transmit ready signal is asserted by the one or more client controllers to indicate the one or more client controllers is ready to transmit data or command bits placed on the data bus and a corresponding receive ready signal is asserted by the master controller to acknowledge receipt of data or command bits placed on the data bus by the one client controller.
The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment which proceeds with reference to the drawings.